Commit ec03c210 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Greg Kroah-Hartman
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staging: fbtft: Rectify GPIO handling 

The infamous commit c440eee1 ("Staging: staging: fbtft: Switch to
the GPIO descriptor interface") broke GPIO handling completely.
It has already four commits to rectify and it seems not enough.
In order to fix the mess here we:

  1) Set default to "inactive" for all requested pins

  2) Fix CS#, RD#, and WR# pins polarity since it's active low
     and GPIO descriptor interface takes it into consideration
     from the Device Tree or ACPI

  3) Consolidate chip activation (CS# assertion) under default
     ->reset() callback

To summarize the expectations about polarity for GPIOs:

   RD#			Low
   WR#			Low
   CS#			Low
   RESET#		Low
   DC or RS		High
   RW			High
   Data	0 .. 15		High

See also Adafruit learning course [1] for the example of the schematics.

While at it, drop unneeded NULL checks, since GPIO API is tolerant to that.

[1]: https://learn.adafruit.com/adafruit-2-8-and-3-2-color-tft-touchscreen-breakout-v2/downloads



Fixes: 92e3e884 ("Staging: fbtft: Fix GPIO handling")
Fixes: b918d1c2 ("Staging: fbtft: Fix reset assertion when using gpio descriptor")
Fixes: dbc4f989 ("Staging: fbtft: Fix probing of gpio descriptor")
Fixes: c440eee1 ("Staging: fbtft: Switch to the gpio descriptor interface")
Cc: Jan Sebastian Götte <linux@jaseg.net>
Cc: Nishad Kamdar <nishadkamdar@gmail.com>
Reviewed-by: default avatarPhil Reid <preid@electromag.com.au>
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210503172114.27891-2-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 0d59ca5a

drivers/staging/fbtft/fb_agm1264k-fl.c

+10 −10
Original line number Diff line number Diff line
@@ -84,9 +84,9 @@ static void reset(struct fbtft_par *par) 


	dev_dbg(par->info->device, "%s()\n", __func__);



	gpiod_set_value(par->gpio.reset, 0);

	udelay(20);

	gpiod_set_value(par->gpio.reset, 1);

	udelay(20);

	gpiod_set_value(par->gpio.reset, 0);

	mdelay(120);

}
@@ -194,12 +194,12 @@ static void write_reg8_bus8(struct fbtft_par *par, int len, ...) 
	/* select chip */

	if (*buf) {

		/* cs1 */

		gpiod_set_value(par->CS0, 1);

		gpiod_set_value(par->CS1, 0);

	} else {

		/* cs0 */

		gpiod_set_value(par->CS0, 0);

		gpiod_set_value(par->CS1, 1);

	} else {

		/* cs0 */

		gpiod_set_value(par->CS0, 1);

		gpiod_set_value(par->CS1, 0);

	}



	gpiod_set_value(par->RS, 0); /* RS->0 (command mode) */
@@ -397,8 +397,8 @@ static int write_vmem(struct fbtft_par *par, size_t offset, size_t len) 
	}

	kfree(convert_buf);



	gpiod_set_value(par->CS0, 1);

	gpiod_set_value(par->CS1, 1);

	gpiod_set_value(par->CS0, 0);

	gpiod_set_value(par->CS1, 0);



	return ret;

}
@@ -419,10 +419,10 @@ static int write(struct fbtft_par *par, void *buf, size_t len) 
		for (i = 0; i < 8; ++i)

			gpiod_set_value(par->gpio.db[i], data & (1 << i));

		/* set E */

		gpiod_set_value(par->EPIN, 1);

		gpiod_set_value(par->EPIN, 0);

		udelay(5);

		/* unset E - write */

		gpiod_set_value(par->EPIN, 0);

		gpiod_set_value(par->EPIN, 1);

		udelay(1);

	}

drivers/staging/fbtft/fb_bd663474.c

+0 −4
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/gpio/consumer.h>

#include <linux/delay.h>



#include "fbtft.h"
@@ -24,9 +23,6 @@ 


static int init_display(struct fbtft_par *par)

{

	if (par->gpio.cs)

		gpiod_set_value(par->gpio.cs, 0);  /* Activate chip */



	par->fbtftops.reset(par);



	/* Initialization sequence from Lib_UTFT */

drivers/staging/fbtft/fb_ili9163.c

+0 −4
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ 
#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/gpio/consumer.h>

#include <linux/delay.h>

#include <video/mipi_display.h>
@@ -77,9 +76,6 @@ static int init_display(struct fbtft_par *par) 
{

	par->fbtftops.reset(par);



	if (par->gpio.cs)

		gpiod_set_value(par->gpio.cs, 0);  /* Activate chip */



	write_reg(par, MIPI_DCS_SOFT_RESET); /* software reset */

	mdelay(500);

	write_reg(par, MIPI_DCS_EXIT_SLEEP_MODE); /* exit sleep */

drivers/staging/fbtft/fb_ili9320.c

+0 −1
Original line number Diff line number Diff line
@@ -8,7 +8,6 @@ 
#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/gpio/consumer.h>

#include <linux/spi/spi.h>

#include <linux/delay.h>

drivers/staging/fbtft/fb_ili9325.c

+0 −4
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/gpio/consumer.h>

#include <linux/delay.h>



#include "fbtft.h"
@@ -85,9 +84,6 @@ static int init_display(struct fbtft_par *par) 
{

	par->fbtftops.reset(par);



	if (par->gpio.cs)

		gpiod_set_value(par->gpio.cs, 0);  /* Activate chip */



	bt &= 0x07;

	vc &= 0x07;

	vrh &= 0x0f;